The overall goal of this project is to understand the response characteristics of neurons in the cochlear nuclei (CN) in terms of their roles in auditory information processing. There are two aspects to the approach to this general goal. In one, the means by which inputs from the auditory nerve (AN) are integrated in CN cells are studied. The focus here is on the cellular mechanisms by which AN spike trains are converted to CN spike trains. The integrative relationships are considered with respect to models of CN cells. In the other aspect, the response properties of CN cells are studied for complex stimuli; this input/output analysis of the CN allows description of information processing activities in terms of preservation and sharpening of information-bearing features of the acoustic stimulus. Three aims are included. 1. Cross-correlation analysis of connected pairs consisting of an AN fiber and a simultaneously-isolated CN cell. This analysis provides information on the organization of inputs to CN cells and on the contribution of individual fibers' spike trains to the responses of the CN cell. 2. Characterization of the spike trains of AN fibers and CN cells in terms of their regulatory of discharge and latency of response. These studies allow development and testing of models of synaptic interaction in the cochlea and CN. 3. Study of the representation of the monaural spectral cues and binaural interaural-level-difference cues for sound localization in the AN and CN. This study will focus on cues produced by directional filtering of the pinna. Hypothesis about specific CN mechanisms for detection, representation and sharpening of sound localization cues will be tested.